A case-control study of maternal risk factors for thyroid cancer in young women (California,United States)

A population-based case-control interview study investigated whether reproductive factors are related to the striking female-over-male excess of thyroid cancer among women of reproductive age in Los Angeles County, CA (United States). As a separate component of that study, mothers of 153 cases and 140 controls who were age 40 or younger at diagnosis or reference date were interviewed by telephone to determine the significance of family and maternal risk factors in the subsequent development of thyroid cancer among the daughters. More case than control mothers experienced miscarriage prior to the index pregnancy (odds ratio [OR]=2.0, 95 percent confidence interval [CI]=1.1–3.5). Increased risk was associated with family history of thyroid cancer or other thyroid disease (OR=2.1, CI=1.2–3.6). More control than case mothers smoked during the index pregnancy (OR=0.6, CI=0.4–1.0); however, among mothers who smoked, case mothers smoked more. Case mothers experienced a greater increase in weight from minimum adult weight to weight at index pregnancy (P for trend = 0.01). Reports from mothers also confirmed the risk associated with the daughter's exposure to ionizing radiation from birth through adolescence; ionizing radiation remains the best-established risk factor for thyroid cancer.This study was funded by program project CA17054 from the National Cancer Institute.     

Retrospective cohort study of risk-factors for esophageal cancer in Linxian,People's Republic of China

A retrospective cohort study of esophageal (including gastric cardia) cancer was conducted to examine dietary and other potential risk factors in Linxian, a high-risk area in P.R. China. Study subjects were identified based on participation in a cytology examination conducted in 1974. They were interviewed in 1989 to obtain information on esophageal cancer risk-factors and identify new cases and deaths. A total of 1,162 subjects from the analytic cohort of 12,693 were determined to have developed esophageal cancer over the 15-year follow-up period. Results indicate that increased age, male gender, a positive family history, low education level, surface-water use, and pork consumption were the strongest risk factors for esophageal cancer identified in this cohort, while use of corn as a primary staple and infrequent consumption of fresh vegetables also were possible risk factors. Traditional or suspected risk factors for esophageal cancer in this and other populations—smoking and alcohol use, and pickled vegetable and moldy food consumption—were not risk factors in this study. Some variation in risk was seen based on the subject's cytology result from 1974. We conclude that dietary factors appear to play a role in the etiology of esophageal cancer in this high-risk population, but are less important than other constitutional factors such as age, gender, and family history.Drs Yu, Li, Wang, Guo, Wang, Liu, and Li are with the Cancer Institute of the Chinese Academy of Medicinal Sciences in Beijing, PRC. Drs Taylor, Dawsey, and Blot are with the National Cancer Institute in Bethesda, MD, USA. Dr Shen is with Henan Medical University in Zhengzhou, PRC. This project was funded partially by contract # NO1-CP-41019 from the US National Cancer Institute.     

Breast cancer in Australian women under the age of 40

Objectives: A case-control-family study of breast cancer in women under the age of 40 was carried out in Melbourne and Sydney, Australia, from 1992 to 1995 to determine the risk factors for these women. Subjects included 467 incident cases identified by state cancer registries and 408 population-based controls. Methods: All participants completed a structured risk-factor questionnaire and family pedigree during an in-person interview. Where possible, cancers in first- and second-degree relatives were verified. Results: Multiple logistic regression analysis showed that the strongest risk factor for breast cancer was a family history of the disease - having at least one affected first-degree relative trebled the risk (relative risk [RR] = 3.3, 95 percent confidence interval [CI] = 1.9-5.8). Risk increased with height by three percent (standard error [SE] of one percent) per cm, and after adjusting for height, there was evidence for a decreased risk in women weighing 73 kg or more. There was an increased risk of breast cancer after the first full-term birth (RR = 1.8, CI = 1.0-3.5) but this risk fell by 30 percent (SE = 11 percent) with each subsequent livebirth. Conclusions: The effects of other reproductive factors and oral contraceptive use, although not nominally significant, were in accord with published findings from similar studies in young women. This study of Australian women has indicated that some risk factors for breast cancer in women under age 40 differ from those reported for older women either in direction (e.g., weight) or relative importance (e.g., family history).     

Dentition,oral hygiene,and risk of oral cancer: a case-control study in Beijing,People's Republic of China

A case-control study of oral cancer was conducted in Beijing, People's Republic of China. The study was hospitalbased and controls were hospital in-patients matched to the cases by age and gender. A total of 404 case/control pairs were interviewed. This paper provides data regarding oral conditions as risk factors for oral cancer, with every patient having an intact mouth examined (pre-operation among cases) using a standard examination completed by trained oral physicians. After adjustment for tobacco smoking and alcohol consumption, poor dentition—as reflected by missing teeth—emerged as a strong risk factor for oral cancer: the odds ratio (OR) for those who had lost 15 – 32 teeth compared to those who had lost none was 5.3 for men and 7.3 for women and the trend was significant (P <0.01) in both genders. Those who reported that they did not brush their teeth also had an elevated risk (OR =6.9 for men, 2.5 for women). Compared to those who had no oral mucosal lesions on examination (OR=1.0), persons with leukoplakia and lichen planus also showed an elevated risk of oral cancer among men and women. Denture wearing per se did not increase oral cancer risk (OR=1.0 for men, 1.3 for women) although wearing metal dentures augmented risk (OR=5.5 for men). These findings indicate that oral hygiene and several oral conditions are risk factors for oral cancer, independently of the known risks associated with smoking and drinking.From the Department of Epidemiology, National Institute of Environmental Health and Engineering, Chinese Academy of Preventive Medicine, Beijing, China (ZT; HH; NS); Unit of Analytical Epidemiology, International Agency for Research on Cancer, Lyon, France (PB; ZT); Beijing Union Hospital (DJ); Cancer Institute, Chinese Academy of Medical Science (JP); Beijing Medical University Stomatological Hospital (MD); Beijing Municipal Stomatological Hospital (SL); University Department of Oral Medicine and Oral Surgery, Bristol Dental Hospital and School, UK (CS); Department of Epidemiology, Harvard School of Public Health (BM; ZT). Address correspondence to Dr Zheng at the Cancer Prevention Research Unit, Yale University, School of Medicine, 26 High Street, New Haven, CT 06510, USA. Dr Zheng was partly supported by a grant from the DuPont Company.     

Tobacco smoking,alcohol consumption,and risk of oral cancer: a case-control study in Beijing,People's Republic of China

A case-control study of oral cancer was conducted in Beijing, People's Republic of China (PRC). The study was hospital-based and controls were hospital in-patients matched for age and gender with the cases. The response rates for cases and controls were 100 percent and 404 case/control pairs were interviewed. Tobacco smoking and alcohol consumption emerged as independent risk factors for oral cancer. For tobacco smoking, the association was considerably stronger for smokers of pipes than for smokers of cigarettes. For all kinds of tobacco, expressed as cigarette equivalents, the odds ratio (OR) for total pack-years smoked, among males, rose from 1.0 in never-smokers to 3.7 (95 percent confidence interval, 1.8–7.4) in the highest quintile of exposure. Similar results were found for females. The association with tobacco consumption was strong for squamous cell carcinoma but there was no trend in risk associated with tobacco for adenocarcinomas and other histologic types. So few women reported consuming alcohol that this variable could be examined only in male. Risk in the highest category of total lifetime intake of alcohol relative to than in lifetime abstainers was 2.3 (1.1–4.8) with a significant trend in risk with increasing dose (P<0.002). The combined effects of tobacco and alcohol appear to be approximately multiplicative in males. The attributable risk of oral cancer for tobacco among tobacco smokers was estimated as 34 percent (45 percent among males and 21 percent among females); for alcohol consumption in males the estimate was 23 percent.Drs Zheng, Hu, and Niu are from the Department of Epidemiology, National Institute for Enviromental Health and Engineering, Chinese Academy of Pieventive Medicine, Beijing, People's Republic of China. Dr Boyle is with the Unit of Analytical Epidemiology, Internationat Agency for Research on Cancer, Lyon, France, where Dr Zheng beld a fellowship. Dr Duan is with the Beijing Union Hospital. Dr Jian is with the Cancer Institute, Chinese Academy of Medical Sciences. Dr Ma is with the Beijing Medical University Stomatological Hospital, Dr Shui is with the Beijing Municipal Stomatological Hospital, Dr MacMabon is in the Department of Epidemiology, Harvard School of Public Health where Dr Zbeng was a graduate student. Address reprint requests to Dr Zheng at the Cancer Prevention Research Unit, Department of Epidemiology and Public Health, Yale University, School of Medicine, B.O. Box 3333, New Haven, CT 06310, USA, Dr Zbeng was supported, in part by a grant from the DuPont Company.     

Occupation,physical activity,and risk of prostate cancer in Shanghai,People's Republic of China

Based on occupational data for all (n=264) prostate cancer cases diagnosed during 1980–84 in urban Shanghai and on employment information from the 1982 census, standardized incidence ratios (SIR) were calculated for occupational groups classified by job type and physical activity level. White-collar workers (professionals, government officials, clerical workers, salespersons) had an elevated incidence of prostate cancer, although the excesses were not significant. In addition, when jobs were classified by time spent sitting or energy expenditure, men employed in occupations with low physical activity levels tended to have moderately elevated risks of prostate cancer. Findings from this study in an area with one of the world's lowest incidence rates of prostate cancer add to the accumulating evidence that jobs with a low level of physical activity are associated with an increased prostate-cancer risk.     

Esophageal cancer in Shanxi Province,People's Republic of China: a case-control study in high and moderate risk areas

Dietary, smoking, and drinking habits, as well as sociopsychological factors and familial history, were investigated in a case-control study on the etiology of esophageal cancer (EC) in two areas of Shanxi (Yangcheng and Linfen), north central China. Data were analyzed from 326 cases and 396 controls. We identified several factors associated with high or low risk; some were common across the areas and others were area-specific. Consumption of millet gruel was associated positively with EC, in a dose-response relationship. An increase in EC risk was seen for consumption of millet soup with noodles, and also with certain sociopsychological factors, in both areas. A large increase in risk was found with consumption of boiled vegetables in Linfen, with a dose-response relationship. EC risk tended to become greater with the increasing intake of moldy foods and of pickled vegetable juice. A positive association between EC risk and family history of EC was observed only in Yangcheng. Soybean consumption was found to be associated with reduced risk. Dental hygiene (brushing teeth) was associated with reduced risk in Linfen. There was a suggestion of increased risk associated with heavy tobacco smoking, but it was not significant in either area. Alcohol consumption had a marginally significant association with risk in the high risk area, but not in Linfen.Drs Y-P Wang, Han, Su, Y-L Wang, and Zhu are in the Shanxi Cancer Institute, PR China. Drs Sasaba, Nakachi, and Hoshiyama are with the Division of Epidemiology at Saitama Cancer Center Research Institute, Japan. Dr Tagashira is in the Saitama Cancer Center Research Institute, Japan. Address correspondence to Dr Sasaba, Ina, Saitama 362, Japan.     

Rh factor, family history and risk of breast cancer: A case-control study in Uruguay

Objective: To explore possible relationships among blood factors, family history of breast cancer (BC) and the risk of the disease, a case-control study was carried out in Montevideo, Uruguay. Methods: Eight hundred and one patients were interviewed, including 252 certified cases of BC and 549 frequency-matched controls. Blood groups (ABO, Rh) were obtained from medical records. Multivariate analyses were performed, adjusting for age, selected menstrual and reproductive factors, and family history of BC as well as of other cancers. Results: We found that the absence of Rh factor (Rh−) was positively associated with the risk of BC (adjusted Odds Ratio [OR] = 1.49, 95% Confidence Interval [95% CI] 1.05-2.11). Stratified analyses by family history of BC showed a strong association for Rh− with a positive history of first degree relatives (OR = 3.17, 95% CI 1.06-9.47). Also stratified analyses by family history of other cancers showed a positive association for Rh− with a positive history of first degree relatives (OR = 2.08, 95% CI 1.05-4.11). Conclusion: Regarding the implications of an inherited factor like Rh and its associations with the family history of BC, it might increase the probability to generate high-risk individuals if further studies confirm the present preliminary findings.     

Green-tea consumption and risk of stomach cancer: a population-based case-control study in Shanghai,China

The effect of drinking Chinese green tea on the risk of stomach cancer was evaluated in a population-based case-control study conducted in Shanghai, China, from October 1991 to December 1993. Eligible cases were incident cases of primary stomach cancer diagnosed during the study period among residents of Hongkou district and Nanhui county aged under 80 years. Controls were selected from the same street or commune where the case resided and were matched to the cases on age (within three years) and gender. A total of 711 cases and 711 matched controls, more than 90 percent of the eligible subjects, completed the interview. Information was obtained on the types of tea used, age when habitual tea drinking started, frequency of new batches of tea leaves used per day, number of cups brewed from each batch, total duration of drinking for each batch, strength and temperature of the tea consumed. Statistical analysis was based on modelling through conditional logistic regression. After adjusting for age, gender, place of residence, education, birthplace, alcohol consumption, and cigarette smoking, the odds ratio (OR) comparing drinkers of green tea with nondrinkers was 0.71 (95 percent confidence interval = 0.54–0.93). The adjusted OR decreased with increasing number of new batches of the green tea consumed each day (P value trend = 0.006). With the largest series of stomach cancer cases to date, this study found green-tea consumption associated with lower risk of stomach cancer. Among drinkers of green tea, the risk of stomach cancer did not depend on the age when habitual green-tea drinking started. Green tea may disrupt gastric carcinogenesis at both the intermediate and the late stages.This work was supported by US Public Health Service grant CA52560 from the National Cancer Institute, National Institutes of Health, Department of Health and Human Services.     

Oral contraceptive use and risk of breast cancer in older women (New Zealand)

the effect of oral contraceptive (OC) use at older ages on the risk of breast cancer was examined in a national population-based case-control study conducted in New Zealand. A total of 891 women aged 25 to 54 years with a first diagnosis of breast cancer, and 1,864 control subjects, randomly selected from the electoral rolls, were interviewed. The relative risk (RR) of breast cancer for women aged 45 to 54 years at diagnosis who had ever used OCs was 1.0 (95 percent confidence interval [CI]=0.77–1.3). There was no significant increase in risk of breast cancer among recent users of OCs of any age. Analyses according to age at first and last use among women aged 40 years and older at diagnosis showed no group with an elevated risk of breast cancer. Women who had used OCs for 10 years or longer after age 40 had an apparent increase in risk (RR=2.7, CI=0.97–7.5), but the trend in risk with duration of use was not significant. These findings suggest that OC use in older women does not affect their risk of breast cancer appreciably, but it is not possible to rule out a modest increase in risk with such use.This research was supported by grants from the Medical Research Council of New Zealand and from the Special Programme of Research, Development, and Research Training in Human Reproduction, World Health Organization.     

A prospective study of oral contraceptive use and risk of breast cancer (Nurses' Health Study, United States)

Results of previous epidemiologic studies have provided reassurance that there is little, if any, increase in risk of breast cancer with oral contraceptive (OC) use in general. However, in several studies, an increased risk of breast cancer has been observed in two subgroups, young women who used OCs for extended durations and in women who used OCs prior to a first-term pregnancy. We evaluated these relationships using data from the ongoing Nurses' Health Study cohort (United States). We documented 3,383 cases of breast cancer from 1976 to 1992 among 1.6 million person-years of follow-up. We observed no overall relationship between duration of OC use and breast cancer risk, even among women who reported using OCs for 10 or more years (multivariate relative risk [RR]=1.11, 95 percent confidence interval [CI]=0.94-1.32). Among women less than 45 years of age, the multivariate RR for using OCs for 10 or more years was 1.07 (CI=0.70-1.65) compared with never-users. The risk associated with five or more years of OC use prior to a first full-term pregnancy compared with never-use was 0.96 (CI=0.65-1.43). Among women less than 45 years of age, we observed no evidence of an increased risk with OC use before a first full-term pregnancy (use for five or more years: RR=0.57, CI=0.24-1.31). Because of the age distribution of our cohort, we were unable to evaluate these relationships among women less than 40 years of age. Our study provides considerable evidence that long-term past OC use, either overall or prior to a first full-term pregnancy, does not result in any appreciable increase in breast cancer risk in women over 40 years of age.     

Biliary tract cancer and stones in relation to chronic liver conditions: A population-based study in Shanghai, China

Biliary tract cancers are relatively rare but fatal tumors. Apart from a close link with gallstones and cholangitis, risk factors for biliary tract cancer are obscure. Chronic liver conditions, including liver cirrhosis, have been linked to a higher risk of biliary tract cancer. In a population-based case-control study conducted in Shanghai, China, we investigated the relationships of a history of chronic hepatitis and liver cirrhosis as well as a family history of liver cancer with biliary tract cancer risk. The study included 627 patients with biliary tract cancers (368 gallbladder, 191 bile duct and 68 ampulla of Vater), 1,037 patients with biliary stones (774 gallbladder stones and 263 bile duct stones) and 959 healthy subjects randomly selected from the population. Bile duct cancer was associated with self-reports of chronic liver conditions, including a history of chronic hepatitis (OR = 2.0, 95% CI 0.9-4.4), liver cirrhosis (OR = 4.7, 95% CI 1.9-11.7) and a family history of primary liver cancer (OR = 2.0, 95% CI 1.0-3.9). The excess risk persisted after adjustment for gallstones and were more pronounced among subjects without gallstones (OR = 5.0, 95% CI 1.3-20.0 and OR = 4.9, 95% 2.0-12.2, respectively). History of liver conditions was also associated with an excess of biliary stones (OR = 1.9, 95% CI 1.2-3.0). No association was found for cancers of the gallbladder and ampulla of Vater. A history of chronic hepatitis and cirrhosis may be risk factors for extraheptic bile duct cancer. Given that chronic infection with hepatitis B virus (HBV) is the most common cause of liver disease in China, serologic markers of HBV need to be measured in future studies to examine the link between HBV and bile duct cancer.     

Non-Hodgkin's lymphoma and family history of malignant tumors in a case-control study (United States)

Using data froma case-control study in the United States (the Selected Cancers Study), weexamined the relationship between non-Hodgkin's lymphoma (NHL) and family history of different cancers. Cases were 1,511 men aged 31 to 59 years and diagnosed pathologically with non-Hodgkin's lymphoma during 1984-88. Controls were men, frequency-matched to cases by age range and cancer registry (n = 1,910). All study subjects with acquired immunodeficiency syndrome were excluded from analyses. Our results showed that the risk of NHL is associated with a history of lymphoma (odds ratio [OR] = 3.0, 95 percent confidence interval [CI] = 1.7-5.2) and hematologic cancer (OR = 2.0, CI = 1.2-3.4) in first-degree relatives after adjustment for age, ethnic background, and educational level. Further analyses were performed for the subgroups defined by age at diagnosis (younger than 45 years cf 45 years or older). The association of NHL with a family history of lymphoma and hematologic cancer was found primarily among men aged 45 and older (OR = 4.1, CI = 1.9-8.8 for lymphoma and OR = 2.3, CI = 1.3-4.0 for hematologic cancer). The association among men aged 45 and older did not vary by whether or not there were any familial patients diagnosed at the age of 45 or older. No significant associations could be found for a family history of lung cancer, breast cancer, prostate cancer, colon cancer, skin cancer, liver cancer, stomach cancer, brain cancer, thyroid cancer, or myeloma. This study suggests that the familial risk of NHL is influenced primarily by hematolymphoproliferative malignancies rather than other cancers. The familial effects of hema-tolymphoproliferative malignancies may be stronger for men aged 45 to 59, compared with those aged 31 to 44.     

Longchain serum fatty acids and risk of thyroid cancer: A population-based case-control study in Norway

Epidemiologic studies have shown an association between seafood consumption and risk of thyroid cancer. Fish meals increase the serum concentrations of the longchain fatty acids, eicosapentaenoic acid (205,n-3) (EPA) and docosahexaenoic acid (226,n-3) (DHA), for days. The hypothesis that serum concentrations of fatty acids may be associated with thyroid cancer risk therefore was tested in a population-based case-control study with 74 cases and 221 matched controls. Seventy-three cases with sera in the Norwegian serum bank (JANUS) were identified in the Norwegian Cancer Registry and matched with three controls, also in JANUS, on age, gender, place of residence, and time of blood sampling. Each case was matched with two controls. Serum concentrations of 11 longchain fatty acids were determined blindly by gas chromatography for all subjects. Controls were divided into three groups with increasing serum fatty acid concentrations, and odds ratios between cases and controls were estimated relative to the group with lowest serum level by univariate and multivariate analyses. The main finding was a significant inverse relation between the sum of arachidonic acid (204,n-6) (AA) and DHA serum concentrations and thyroid cancer risk. The significance of this association was weakened when the analyses were restricted to the papillary type of thyroid carcinoma. It was of the same order of magnitude whether the period between blood sampling and diagnosis was greater than eight years, or eight or less years. High EPA/AA ratio, indicating consumption of fish fat, was not associated significantly with increased thyroid-cancer risk. These data indicate that the association between seafood ingestion and increased thyroid-cancer risk may not be caused by the marine fatty acids.     

A pooled analysis of case-control studies of thyroid cancer. VII. Cruciferous and other vegetables (International)

OBJECTIVE: To investigate the association between cruciferous and other vegetables and thyroid cancer risk we systematically reanalyzed the original data from 11 case–control studies conducted in the US, Asia, and Europe.METHODS: A total of 2241 cases (1784 women, 457 men) and 3716 controls (2744 women, 972 men) were included. Odds ratios (OR) and the corresponding 95% confidence intervals (CI) were estimated for each study by logistic regression models, conditioned on age and sex, and adjusted for history of goiter, thyroid nodules or adenomas, and radiation. Summary ORs for all studies combined were computed as the weighted average of the estimates from each study.RESULTS: A decreased risk for the highest level of cruciferous vegetable intake, as compared to the lowest, was observed in Los Angeles, Hawaii, Connecticut, southeastern Sweden, Tromsø, and Switzerland; the OR were above unity in Japan and Uppsala, whereas no material association was found in northern Sweden, Italy, or Greece. The OR values for all studies combined were 0.87 (95% CI 0.75–1.01) for moderate and 0.94 (95% CI 0.80–1.10) for high cruciferous vegetables intake. The results were similar in studies from iodine-rich areas and endemic goiter areas, and were consistent when the analysis was restricted to papillary carcinomas and women. The summary OR values for vegetables other than cruciferous were 1.04 (0.88–1.22) for moderate and 0.82 (0.69–0.98) for high consumption.CONCLUSIONS: This combined analysis indicates that cruciferous vegetables are not positively related to thyroid cancer risk. Their effect does not seem to be substantially different from that of other vegetables, which appear to be protective on this cancer.     

应用GM(1,1)灰色模型预测全国甲状腺癌发病趋势

目的:探讨应用GM(1,1)灰色模型在全国及分性别、地区的甲状腺癌发病率预测中的可行性,为制定措施预防甲状腺癌发病提供参考.方法:甲状腺癌发病数据来源于2008至2018年《中国肿瘤登记年报》,通过建立模型评价其预测效果并预测未来5年的发病率.结果:全国及分性别(男、女)、地区(城市、农村)甲状腺癌发病率预测模型分别为...     

Alcohol dehydrogenase 1B (ADH1B) genotype, alcohol consumption and breast cancer risk by age 50 years in a German case-control study

In a population-based study of 613 cases and 1082 controls, alcohol dehydrogenase 1B (ADH1B) genotype was not an independent risk factor for breast cancer, although the possibility was raised that it modifies risk associated with high levels of alcohol consumption (OR 1.1, 95% confidence interval (CI) 0.8-1.6 for ADH1B*1/*1 genotype vs 0.2, 95% CI 0.1-1.0 for ADH1B*2 carriers).     

Dietary relationships with early onset (under age 45) breast cancer in a case-control study in the United States: influence of chemotherapy treatment

Methodologic investigations have addressed selection and recall biasin case-control studies of diet and breast cancer, whereas the effect ofdisease progression and medical treatment on estimates of dietary intake hasbeen largely overlooked. In a multicenter, population-based case-controlstudy of breast cancer in the United States, 1,588 newly diagnosed cases and1,451 controls completed a self-administered food-frequency questionnaire.Initial evaluation suggested increased risk related to high intakes ofcalories, carbohydrates, fat, and protein. All nutrient associations werediminished after adjustment for calories. Evaluation by stage of diseaserevealed no relation of calories to risk among women with in situ disease,but elevated risks among women with localized (odds ratio [OR] = 1.33, 95percent confidence interval [CI] = 1.0-1.7 highest cf lowest quartile) orregional and distant disease (OR = 1.79, CI = 1.3-2.4). Further evaluationshowed that the increased risk a ssociated with calories was restricted tocases who reported having been treated with chemotherapy (OR = 1.66, CI =1.3-2.1). A gradient of increasing risk with time interval from diagnosis tointerview suggested the chemotherapy regimen itself and not necessarilycharacteristics of tumors requiring this treatment was responsible for theobserved increased risk. These results indicate that epidemiologic studies ofdiet and breast cancer, particularly among young women, should evaluatepossible bias related to post-diagnosis influences.     

Maternal pregnancy hormone levels in an area with a high incidence (Boston, USA) and in an area with a low incidence (Shanghai, China) of breast cancer

Characteristics probably associated with the fetal hormonal milieu have recently been shown to increase (birth size indicators, prematurity, neonatal jaundice) or decrease (pregnancy toxaemia) breast cancer risk in the female offspring. However, it is unknown whether differences in pregnancy hormone levels may contribute to the marked geographical variation in breast cancer incidence. We have compared, in a highly standardized manner, pregnancy hormone levels in a population with high incidence and one with low incidence of breast cancer. Three hundred and four pregnant Caucasian women in Boston and 334 pregnant Chinese women in Shanghai were enrolled from March 1994 to October 1995. Levels of oestradiol, oestriol, prolactin, progesterone, human growth hormone, albumin and sex hormone-binding globulin were measured in maternal blood at weeks 16 and 27 of gestation and compared between the two study sites using non-parametric Wilcoxon''s rank-sum test. Demographical, anthropometrical and pregnancy characteristics were ascertained through interview, and relevant variables concerning delivery and the newborn were abstracted from medical records and paediatric charts. During the first visit, median serum levels of all studied hormones were statistically significant, and in most instances substantially, higher among Chinese women, who have a low incidence of breast cancer, compared with American women, who have a high incidence of breast cancer. An analogous pattern was evident during the second visit, although the relative differences tended to be smaller. Further research is needed to identify lifestyle or other exogenous determinants of pregnancy hormone levels, as well as possible mechanisms by which they may influence carcinogenic processes in the breast and possibly other organs. © 1999 Cancer Research Campaign